Huddersfield back-rower Dale Ferguson will miss the rest of the season, while prop Paul Clough has been ruled out for a month.
Scotland captain Ferguson, 31, has made just one appearance for the Giants this year after a bad run of luck with injuries, but ended that game against Wakefield with blurred vision.
And Clough, 31, has played 13 games for the Giants in 2019 because of injuries and will miss at least the next month with a broken hand.
Huddersfield coach Simon Woolford told BBC Radio Leeds: “Cloughy will be missing for four to six weeks.
“Fergy’s unsure about what’s wrong. He’s still got symptoms, he’s seeing some kind of neurologist in the next little bit to find out what actually happened.
“I wouldn’t anticipate him being back and we’ll be lucky to see him again this year, he’s been through a traumatic couple of weeks.
“I’ve got guys like Matty English to come back in contention this week [against Hull KR] and Adam Walne is fit so at least we have got a little bit of depth in the front-row department at the moment.”